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RADIO BROADCASTDECEMBER, 1927

WILLIS KINGSLEY WING, Editor

KEITH HENNEY EDGAR H. FELIXDirector of the Laboratory Contributing Editor

Vol. XII, No. 2

Cover Design - - - - From a Design by Harvey Hopkins Dunn

Frontispiece - Television Apparatus of a European Scientist 102

Television in Europe William J. Brittain 103

The March of Radio - - - An Editorial Interpretation 105How the Radio Commission Can Set Radio "Radio Industry" Standards

to Rights Why the South Has Few StationsWhat Can the Commission Do? The New WEAF Transmitter$100,000 to Improve Broadcasting News of the Patent FieldWhat to Tell the Consumer and Where The Month in RadioWhat Broadcasters Want

Applications of the Four-Electrode Tube Theodore H. }Ja\\en 109The Phonograph Joins the Radio Set - ' ' i la

Make Your Own Radio Picture Receiver - - Austin G. Cooley 114Beauty The Keynote in the New Radio Receivers 118What B Device Shall I Buy? Howard E. Rhodes 120

Measuring the "Gain" of Your Radio Receiver Keith Henney 123Book Reviews . , , , j^ I^

Inventions and Patents, Wright The Story of Radio, Dunlap

Loud Speakers - 126

Power Devices 127Facts About the Fada

"Special" Receiver - John F. Rider 128

Our Readers Suggest - 131How to Improve Your Old Receiver - Edgar H. Felix 133A Quality Five-Tube A. C. Receiver James Mil/en 135A New "TwO'Ten" Power Amplifier William Morrison 138The DX Listener Finds a Champion - - - John Wallace 140

"The Listeners' Point of View"

As the Broadcaster Sees It Carl Dreher 142Radio As an Electro-Medical Cure-Ail Piezo-Electric Control of StationsSome Catalogues The Small Broadcaster

"Radio Broadcast's" Laboratory Data Sheets - - - - - 146No. 145. Loud Speakers No. r49. Circuit Diagram of an A.C. AudioNo. 146. B Power Device Characteristics ^ AmplifierVT ..,-, . No. 150. Oscillation ControlNo. 147. Gain No. I 5 r. Single ControlNo. 148. An A.C. Audio Amplifier No. 152. Speech

Manufacturers' Booklets Available - - - '152" Radio Broadcast's" Directory of Manufactured Receivers - - 154What Kit Shall I Buy?

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- - 170

From the Manufacturers '.' 174

AMONG OTHER THINGS. . ."DROBABLY the most interesting article in this issue from*- the point of view of the experimenter is the constructionaldata and operating and assembly instructions on the Cooley"Rayfoto" radio picture receiver. By the time this magazineis in the hands of its readers, all the essential apparatus will beavailable on the market and nothing will delay the experimenterin his experience in this new field. RADIO BROADCAST is glad toforward the names of readers who are interested in receivingprinted matter and late bulletins to manufacturers who aresupplying the various parts for the "Rayfoto" apparatus. Afterthe appearance of Mr. Cooley's November article, a great num-ber of our readers wrote us for this information which hasbeen supplied. A letter should at once be addressed to theundersigned, asking for additional data in case you have notalready written.

V\ WASHINGTON is the center of interest these days, what* * with the International Radio Conference and the changes

in the Federal Radio Commission. The death of CommissionerDillon is a great loss to radio in the United States and it will benext to impossible to fill his place. The resignation of Com-missioner Bellows removes one of the ablest members of theCommission, but President Coolidge has filled his place throughthe appointment of Sam Pickard, former secretary to the radiobody. Mr. Pickard is a likeable and able individual and webelieve his appointment is a wise one. Carl H. Butman, ofWashington, was appointed as Secretary to succeed Mr. Pick-ard. Mr. Butman has long served RADIO BROADCAST as itsWashington news representative and we are indeed pleasedthat the Commission has so wisely chosen a man who knowsradio problems so well.

A WORD about the authors in this issue: William J.** Brittain is an English writer on radio and scientifictopics who has just returned from a European trip to see whatis being done in television. Theodore H. Nakken is a researchengineer for the Federal Telegraph Company. He is a pioneerin photo-electric cell work and is unusually familiar with radioprogress abroad. Austin Cooley, whose "Rayfoto" pictureapparatus has attracted national attention, is a native of thestate of Washington, received his technical training at M. I. T.,and except for his trip in 1916 with the MacMillan Arcticexpedition, has been in New York for the past four years.John F. Rider is a well-known New York technical writer whois at work on an interesting series of "fact" articles about manu-factured receivers.

T^HE next issue will contain another story about the Cooley*

"Rayfoto" radio picture system and its operation, as wellas interesting data about push-pull power amplification. An-other of Mr. Rider's articles about manufactured receivers willbe featured as well as a wealth of constructional matter.

WILLIS KINGSLEY WING.

Doubleday, Page & Co.MAGAZINES

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TELEVISION APPARATUS OF A EUROPEAN SCIENTIST

HpH IS equipment constitutes the television receiver developed by M.1 Holweck, who is collaborating with Edouard Belin in the design of

television equipment. M. Holweck is specializing in the receiving side ofthe installation. The received picture appears on the small circular screenat the top of the receiver shown in this illustration. Numerous otherEuropean scientists are devoting their time to the development of tele-

vision schemes, and many and promising are the reports emanating fromthe various laboratories. M. Belin is, of course, a Parisian and hasdone most of his work in France. The short story which begins on the suc-ceeding page is from the pen of one who has visited many of the pioneersin the television field in Europe, and the information has, therefore, beenobtained at first hand.

VON M1HALY S TRANSMITTING APPARATUS

TELEVISION IN EUROPEBy WILLIAM J. BRITTAIN

rHAT is Europe doing towardsthe furtherance of television?America already knows quite a

lot about the work of Baird, and the publiccompany formed to develop his machineshas made his name known in most countries.But aside from this, little is known of theprogress of the many experimenters in thisfascinating art on the other side of theAtlantic.

Recently the author went from Englandto find out what the Continental men aredoing, what their apparatus is like, andwhether they are preparing a surprise forthe world, and in Berlin was found the manpreparing the surprise. He is Denes voniYiihaly, a young Hungarian, and chiefconsulting engineer to A. E. G. (the GeneralElectric Company of Germany). Anengineer brought from America for thepurpose is making a simplified version ofVon Mihaly's apparatus to be shown inBerlin and London as a preliminary toforming television companies there.The vital feature of Von Mihaly's method

is an oscillograph which consists of atiny mirror mounted on twin wires. Themirror vibrates between two electro-mag-nets at speeds which sometimes reachthousands of times a second. Light re-flected from the object a face, a scene,or whatever it may be is focussed by aspecially constructed set of Zeiss lenses upon

the mirror. The mirror, vibrating rapidly,sees each point of the object in turn, in themanner necessary for television, and flashesit to a photo-electric cell.Von Mihaly has made his own cell, and

it sends out currents corresponding ex-actly to the intensity of light or depthof shadow of each tiny point as it isreflected upon it.

In his receiving apparatus Von Mihalyagain uses vibrating mirrors. An electriclamp, shining brightly or becoming dim asthe current from the transmitter is strongor weak, is concentrated by lenses uponmirrors which repeat the action of themirror at the sender and zig-zag a beam oflight over a ground glass screen. The vary-ing light beam, covering the screen eighttimes a second, makes up the picture.To ensure that the sending and receiving

mechanisms are working exactly in timeso that the mirror at the receiving end isshining light upon the centre of the screenat the same fraction of a second as the mir-ror at the transmitting end is "seeing" abright part in the center of the objectVon Mihaly uses a tuning fork arrangementon the same principle as those that havebeen used by experimenters in photo-telegraphy. A tuning fork in the receiver,kept vibrating by an electromagnet, actsas a switch, regulating current to other

magnets which allow a wheel to progress

one cog for every impulse, and so regulatethe vibrations of the mirror. The apparatusat each end now fills a table, but VonMihaly says he can simplify it to work asa home set in conjunction with a one-tuberadio receiver.

Behind this assurance is a secret. Thesecret is in a small black cylinder,' fiveinches by two and a half inches. The inven-tor calls it his "little black wonder." Hewill not tell the world what is inside, buttold the author that with it it is possibleto do away with the great amplifiers neces-sary in other systems.

"Television sets for the home," he said,"

will be simple and yet give a boxing matchor a horse race. They will be sold in a fewmonths for the equivalent of a hundreddollars."

Von Mihaly has been working for thir-teen years on television. He first becameinterested when he was twenty, after hear-ing a lecture on photo-telegraphy by Pro-fessor Arthurn Korn. He carried on his workfor the Austria-Hungarian governmentduring the war, and on July 7, 1919, gavehis first crude demonstration of television.Ministers in the laboratory of the TelephonFabrik in Budapest then saw on a screenthe images of the letters M. D. and REXtransmitted from the young engineer'shome laboratory in another part of thecity.

104 RADIO BROADCAST DECEMBER, 1927It was the writer's privilege to be present

at a recent demonstration of Mihaly's ap-paratus. The results obtained were con-siderably better than those of the earls-demonstrations referred to above, and theimages were clearer than those seen by theauthor on Baird's screen. On the pictureof a "televised" boy it was possible to seethe collar, the wavy outline of the hair,the shape of the ear, the forehead, the

eye, the nose, and the mouth, the lattermerging'into shadow on the left side of theface.

OTHER EXPERIMENTERS

PROFESSOR Max Dieckmann, whom1 met in his station near Munich,

Germany, has up to the present no resultlike this to show. He has achieved results,but has scrapped the transmitter and otherapparatus that gave them.

"I used mirrors," he told me, "but Icame to the conclusion that no mechanismcould ever be made light enough and ac-curate enough for television. I am thereforetrying to make use of electrons. By twoelectro-magnets, alternated by currents ofdifferent frequencies, I make the stream ofelectrons or the cathode ray zig-zagover the object, and I am now experiment-ing with devices to register the result ofthis

'exploring.'"With electrons I think I have the real

instrument for television. Electrons arealmost weightless and can travel at anyspeed we need. All mechanism has a weightand inertia that in my opinion will alwaysdrag down efforts at perfect television. Byperfect television I mean, of course, the

reception of images as fine as publishedphotographs. It is possible now to havecrude television. You can have a picture onas large a screen as you like, but the largerthe screen is the larger must be the patchesmaking up the picture. Distance of trans-mission, too, offers little difficulty. We mustconcentrate on producing a finer image, andI believe electrons will enable us to do it."

Professor Dieckmann is retaining his

PROFESSOR MAX DIECKMANN

former receiver which already uses elec-trons. The receiver is like a bottle. The re-ceived currents vary the flow of electronsfrom a tube fixed to the neck of the "bot-tle." By magnets similar to those in his newtransmitter the varying flow of electrons ismade to zig-zag over a screen at the bottomof the

"

bottle"

which glows as the electronstouch it. When a strong current, showingthat a light part of the object is being en-countered at the transmitter, sets off aheavy flow of electrons, the screen glowsstrongly at that part, and the glowingpatches make up the picture.With Mr. Rudolf Hell, his chief assistant,

Professor Dieckmann is working with en-thusiasm at his latest apparatus.

Mirrors form an essential part of theapparatus of M. Edouard Belin, the scien-tist famed for his systems for photo-telegraphy, who has large stations at LaMalmaison, near Paris. M. Belin inspiredcartoons with a television machine thirtyyears ago. His latest apparatus looksbusinesslike.

VON MI-H A L Y ' STELEVISIONRECEIVINGAPPARATUS

Two rectangular mirrors, about half aninch long, set at right angles, are made tooscillate by cranks and connecting rodsdriven by an electric motor. A beam of lightshines on the mirrcrs and is reflected zig-zag in the usual way. For his object M.Belin uses his hand. Light from the handas the beam passes over it is caught by aneighteen-inch concave mirror at the bottomof a drum which concentrates the light on aphoto-electric cell held by an arm half-waydown the drum. With this apparatus, M.Belin told me. he can record fifty thousandflashes of light and shade a second.M. Holweck, collaborator with M.

Belin, is responsible for the receiver. He hasdesigned a special form of cathode rayoscillograph in which as complete a vacuumas possible is kept by an air pump, alsoof his own design. M. Holweck is workingto perfect the fluorescent screen so that itwill vary its glow exactly according to thestrength of the stream of electrons. He hasalso made the apparatus more sensitive sothat a difference of potential of five voltsbetween the grid and the filament will ab-solutely cease the flow of electrons. Thismeans that slight differences of light andshade in the object, and therefore, tinydifferences in the current received, are re-corded on the screen.

Promising results are being obtained. Atpresent M. Belin is transmitting only thesilhouettes of his hand. On the screen theoutline of the hand can be seen clearly.The hand can be seen to move, and thefingers to bend. A silhouette of the profileof a face, and a simple photographic nega-tive, have been transmitted with equalsuccess.

"Our work is progressing gradually" saidM. Belin. "We have found it better to passover the object a bright spot of light ratherthan illuminate fiercely the whole object.It we used flood lighting to obtain the samebrilliancy as our spot light gives us over a

person's face the intensity would be insup-portable.

"

Earlier in the year we were sending overour object in a thousand points; now wehave reached two thousand five hundred.We cover the object eight times a secondwhich means that in our ordinary experi-ments twenty thousand signals are flasheda second. We are greatly encouraged by ourpresent results. In a few months we shouldhave something to offer the world."

This is the stage European inventors havereached. Each one of them is watching care-fully every step forward by other workersand trying to go a step further. Von Mihalyis confident that all his system needs nowis to be put on the market. Dieckmann andhis young assistants are working quietlybut eagerly. And all the time I was at theestablissement Edouard Belin I was filledwith the boyish enthusiasm which per-meates the atmosphere there.Of hopes and plans it would be possible

to write pages but in this article an attempthas been made to keep plainly to facts tolet America know just what Europe isdoing in television.

THK MNKWS AND IN rmPUH'ATIQN OK rilUUJ-'NT PAhlQ EVENTS

How the Radio Commission Can Set Radio to Rights

A THE peak of the radio seasonapproaches, we look upon the situa-tion with considerable satisfaction.

Last year, broadcasting was in chaos andthe Radio Act had not been passed; thisyear, progress has been made in the di-rection of restoring order. Public interest inradio is at a maximum; the Radio Show atNew York broke all records for attendanceat an industrial exposition. Manufacturersand dealers report brisk sales. Broadcastingnow has the stimulus of two competingchains. Everywhere there is activity andprogress.The only sore spot in the radio situation

is in the regulation of broadcasting. TheCommission went about its task with dili-gence as soon as it was formed. It clearedthe Canadian channels and put the stationsback on even ten-kc. channels. Then itspaced the New York and Chicago broad-casters at fifty-kc. intervals, forcing timesharing in some cases to make it possible.After these commendable steps had beentaken, the Commission confined its activi-ties to juggling a channel here and switch-ing a station there.We understood that the assignments of

June 15 were merely an experiment, a stop-gap measure effective only until a compre-hensive plan of allocation could be workedout, which would mean an end to theheterodyne whistle. The persistently optim-istic announcements of the Commission thatthe broadcasting situation is now remediedgive the impression that the Commissionconsiders its major task completed.At the opening of the Radio World's

Fair, Admiral Bullard pleaded for moretime to give the Commission an opportun-ity to do its work; at the Radio IndustriesBanquet, he made numerous proposals tothe radio industry, many of them no lessthan amazing, but nowhere have we had asimple, direct statement of the future plansof the Commission. Does the Commissionconsider its task virtually competed orwill it devote itself to a radical improvementof broadcasting conditions?The Admiral's speech at the banquet

contained some striking indications. Briefly,he stated that broadcasters should find away to fix the responsibility for statementsmade in radio advertising; that direct ad-vertising stations should be taxed; thatradio ought to be a public utility regulatedby public service commissions; that pro-vision should be made to link up broad-casting for national sos calls, perhaps forsuch occasions as the loss of the President'sracoon; that motors for electric elevatorsshould be re-designed; and most ingenuousand amazing, that receiving sets should beequipped with crystals to permit of greaterselectivity.A few words at the very end of this as-

tounding speech were devoted to the Com-mission's plans. With regard to the highpower stations serving the long distancelistener, "the Commission is looking for-ward to a time when the listener, on anynight of good reception, can hear broad-casting stations from the Atlantic to thePacific, from Canada to Mexico, withoutinterference, on channels cleared for them,not by arbitrary rulings of the government,not by fixed and necessarily discriminatingclassifications, but by the normal, logicalprocess of demonstrated fitness and capac-ity to render a great public service. Such adevelopment is entirely practicable on thebasis of allocations now in force. It requiresno sweeping changes, but only a clear pic-ture of the ideal to be attained, and a steadycareful improvement of existing condi-tions. ..."

Thus the ingenious Commission will by"orderly and natural, rather than by auto-cratic and arbitrary methods" bring us

A RADIO TOUR OF THE CONTINENTCapt. L. F. Plugge, an English radio enthusiast,spent the months of July and August on a tourwhich the accompanying map shows. There weretwo radio-equipped cars, one of which is illus-trated. Each had a loop-operated super-hetero-dyne and a short-wave transmitter operating on6660 kc. (45 meters). Intercommunication wasattempted and reception conditions along the

route noted

these ideal listening conditions. No one,unless it be the broadcast listener, will beimposed upon; only stations which electby natural processes to eliminate them-selves will be taken off the broadcastinglists.

The listener unless he lives within theshadow of a broadcasting station, that is,in that short distance which engineers liketo call the service range, must put up withdisagreeable heterodyne whistles. Only ifwe use

"arbitrary" methods, which meansactually applying the regulatory powerswith which the Commission is endowed,can we hope for fewer stations. The naturaltendency is toward increasing the numberof stations and the power they use. TheCommission leans upon a broken reed, if itexpects "normal, logical processes" toeliminate stations. Rubber spine methodscannot help the broadcasting situation.There is only one solution, which we repeat,like Cato and his

"Carthage must be des-troyed," and that is the elimination of atleast four hundred broadcasting stations.

What Can the Commission Do?ECTION IV of the Radio Act author-izes the Commission to classify broad-

^^casting stations, to prescribe the

nature of service rendered by each, to assignbands and powers, and to determine thelocation of stations. There is no limitationon how far it may go in its work of classi-fication.

Why does not the Commission use thesepowers? Why does it not classify broad-casting stations as (i) national, (2) regional,(3) local; divide the country into geographi-cal areas and prescribe exactly how many

106 RADIO BROADCAST DECEMBER, 1927stations of each class shall be licensed ineach of those areas?

Public convenience and necessity clearlyestablish the point that interference amongstations should not be tolerated and cer-tainly the Commission should be competent,if it earns its keep, to determine how manystations of various powers will be accom-modated in the present broadcasting band.In fact, all of these points have been ana-lyzed for it by qualified experts in preciseand unequivocal terms.NATIONAL STATIONS, to which exclusive

channels should be assigned, might be de-fined as follows: (i) Power, 10,000 watts orover; (2) Service, fifty hours a week ormore; (3) Location, at least ten miles fromall centers of 100,000 or more populationand at a point more than fifty miles fromthe nearest national station and not within200 miles radius of more than five nationalstations.

REGIONAL STATIONS, sharing channelswith other regional stations more than1000 or 2000 miles distant: (i) Power,2000 to 5000 watts; (2) Service, at leasttwenty-five hours a week, and (3) Location,not more than 100,000 population withina five mile radius, nor more than five re-gional stations within 100 miles.LOCAL STATIONS: (i) Power, between 250

and 500 watts; (2) Service, at least twenty-five hours; and (3) Location, such that thereare not more than five local service stationswithin a hundred mile radius.Such a program would, of course, require

the elimination of stations in a few of the

congested areas, a blessing to the radioaudience. The stations so eliminated neednot go out of business, but merely con-solidate with others serving the same area.Stations of less than 25O-watt power shouldbe ruled off the air at once, not because theythemselves contribute seriously to con-

gestion but because their channels mightbetter be assigned to national or regionalstations.

Concrete suggestions, which are not onlylogical, but also require the exercise of someof the

"arbitrary" powers conferred uponthe Commission by law, may be in order.We respectfully suggest the promulgationand actual observance of regulations for theaccomplishment of four objectives, the con-stitutionality of which cannot be ques-tioned:

i. ALL STATIONS should be required toadhere to their frequencies and those failingto do so, after occupying their assignedchannels for more than thirty days, shouldbe fined $500 for each violation noted,without any further consideration of theircases. The Commission has been buncoedby whining station managements into thebelief that staying on a channel requiresextraordinary equipment and engineeringgenius. A station failing to adhere to itschannel is not technically competent andnot worthy of a franchise on the air.Furthermore, after its fourth offense, astation's license should be cancelled, with-out further consideration of the case. Theether space thus regained should not beassigned to a new ether nuisance, but

A COMPLETE RADIO INSTALLATION ON AN AIRPLANEAlthough the l/ille de Paris, the Sikorsky airplane built for Captain Fonck, the noted French flier,never started toward Paris, plans for the flight were exceptionally complete. Top right shows thesmall transmitter and a larger set below it. In the center is a regenerative receiver and at the extremebottom, the antenna reel. The motor generator unit is at the extreme left and supplies plate currentfor the transmitter. The generator and propeller can be swung out through the fuselage when in use

utilized in relieving congestion where itexists. The Commission's leniency withregard to channel wobbling, to which itattributes practically all heterodyning, isa remarkable example of unwarrantedbashfulness and consideration the stationsdon't deserve. The five hundred dollarfine for each violation of the Commission'sregulations gives the Radio Act plenty ofteeth but, to our knowledge, the Commis-sion has never tried them out.

2. THE COMBINATION and consolidationof broadcasting in congested areas shouldbe encouraged by guaranteeing to the con-solidators the combined broadcasting priv-ileges of the stations so consolidated. For

example, four, full time, 5OO-watt stations,combined into one, should be permitted apower increase to 2000 watts, or two, half-time stations, forming one, should receivefull time. Furthermore, all local and re-gional stations, not sharing the same chan-nel, which combine, should be guaranteedprivileged consideration on the basis of

program merit, should they seek to securefull time on a single channel by challenginganother station.

3. POWER INCREASES to local andregional stations shall not be granted wherecongestion exists, unless other stations,having a power equivalent to the increase,be absorbed. Thus, for example, for a thous-and-watt station in New York to jump to1500 watts, it should be necessary for it toabsorb a 5OO-watt station.

National stations, on the other hand,serving large areas, should be encouragedto increase power, because they requireclear channels and failure to employ themaximum power means that they are notmaking full use of the channel assigned tothem.

4. THE COMMISSION, empowered toassign hours of broadcasting to stations,should conserve ether space by limitinglicenses only to hours actually used by thestations concerned. It has left problems oftime division to the stations themselves,instead of utilizing its power to help in re-lieving congestions. There are many broad-casting stations which are assigned fifty percent, of the time on a channel which useonly ten per cent, of it, while the other sta-tion on the channel is required to remainsilent, although it has program material tofill the unused time. In congested areas, theassignment of the time should be basedupon the average hours which a stationbroadcast over the same period in the pre-ceding year. Increase over this time shouldbe granted only upon the basis of programmerit and service, or the unused time heldto encourage consolidations and to accom-modate other stations.The present assignment of forty channel:-

to New York and Chicago, nearly half theether space in the eastern part of the UnitedStates, is an imposition upon the listener.Yet new stations are being licensed in NewYork and Chicago, although six stations ineach of those cities have coralled ninetyper cent, of the audience. This concentra-tion of broadcasting facilities in two centers

DECEMBER, 1927 DEATH OF RADIO COMMISSIONER DILLON 107

of population forces the rural listener to

contend with heterodyning all over thedials and precludes power increases in ruralareas where better and bigger stations are

actually needed.The Federal Radio Commission has

worked long and hard with its problem.It has done the best possible job withoutseriously disturbing or curtailing the priv-ileges of the broadcasting station owners.

But, so long as it fails to regard its duty as

serving the interests of the listening public,and fails to use the ample powers conferred

upon it by the Radio Act to reduce thenumber of stations on the air, ether con-gestion will remain the unhealthy diseaseof the broadcasting situation.

$100,000 to Improve Broadcasting

THENational Association of Broad-

casters appropriated the sum of

$100,000 to make a scientific studyof broadcasting. It plans to employ fieldengineers and program specialists to visitindividual stations throughout the country.The procedure of the Association in theeffective utilization of this fund has not

yet been established. If it is sensibly ad-ministered, very valuable contributionscan be made in the technical, economic andprogram problems of the broadcaster.From the technical standpoint, studiomethods, as they affect transmission qual-ity, and the correct operation of the broad-casting stations to help in eliminating ether

congestion are fruitful subjects for research.The Association might well help in de-termining just what the capacity of thebroadcasting band is with regard to power,service range and geographical location ofstations.

In the field of program technique, critical

study of the outstanding features and sys-tematic examination of voice and musicalinstruments which make good broadcastingcould be very helpful. An investigation ofthe possibilities of building high gradeprograms by the use of recording methods,as suggested by Edgar H. Felix in a speechbefore the Association, might also bestudied with a view to investigating itspracticability. Mr. Felix suggested the re-

cording of "scenes," blending the voices of

speakers and pick-up music through mixingpanels and the "editing" of programs muchas films are cut and assembled, until theideal feature is assembled. When thus workedover and perfected, it may be presented asoften and through as many stations as itspopularity warrants, without further costfor talent. This suggestion may result notonly in better planned and coordinated pro-grams, but it may help to reduce the mount-ing wire costs which commercial broadcast-ers now meet.

In the field of commercial broadcasting,a close study of the methods used to associ-ate the commercial program with the pro-duct of its sponsor and to secure the mosteffective results in a manner pleasing to thelistener might help to increase the effective-ness of commercial broadcasting, an end

Henry Miller

THE LATE COL. JOHN. F. DILLON

Colonel Dillon, member of the Federal RadioCommission from the Pacific Coast, died early inOctober. His loss will be keenly felt by theCommission and the radio world at large. Apractical radio man of wide experience, ColonelDillon had served in various technical capacitiesin the Signal Corps, and as radio inspector incharge of the Eighth District when headquarterswere in Cleveland in 1913 and 1914. He was latertransferred to San Francisco as Radio Supervisorfor the Sixth District and it was from this dutythat his appointment as a Radio Commissionercalled him. His wide practical experience withgovernment, amateur, and commercial radiomade Colonel Dillon one of the most valuable

members of the Radio Commission

which is necessary to aid economic stabiliza-tion of broadcasting stations.The National Association of Broadcasters

is to be commended for its foresight in mak-ing this substantial expenditure, which islikely to be returned many fold throughbetter broadcasting and larger audiences.

What to Tell the Consumer AndWhere

ATLICTEDwith the expanded cran-

iums resulting from mushroomgrowth, the larger manufacturers of

the radio industry are often flattered into

advertising excesses which ultimately causefinancial embarassment. As typical of thistrend, we received a dealer notice, not longago, describing a new type of A, B, and Cpower device which was to make its debutto the world principally through three pub-lications having a combined circulation ofover three million copies. Although a

prophet is not often recognized in his own

country, so frequently has the folly of plung-ing into expensive national mediums beendemonstrated to the radio industry, thatmost manufacturers first make an effort tosell the merits of their products among themore influential radio listeners.The general public has been too fre-

quently fooled by innovations to becomeimmediate buyers through the medium ofan advertising flash in national weeklies.

They are inclined to consult the most ex-pert enthusiast whom they can reach beforethey are willing to risk their money on a

device which may fail. The more successfulmanufacturers establish

.

their productsamong the more influential groups of radiobuyers before they plunge recklessly intonational campaigns in behalf of productswhich do not have behind them the weightof acknowledged approval of the better in-formed radio enthusiast. The influence ofthe radio enthusiast, like halitosis, is oftenthe insidious element which prevents thesuccess of the national advertising cam-

paign which is not supported by the good-will of well informed broadcast listenersand constructors.

WHAT BROADCASTERS WANT

A LIST of hearings scheduled by the FederalRadio Commission early in October indi-cates the evils of requiring hearings upon all

applications, regardless of their merit. For ex-

ample, WBAW, Nashville, Tenn., a loo-watt sta-tion, operated by a drug concern, seeks to in-crease its power to 10,000 watts, making itnecessary for nineteen stations to defend them-selves against this unwarranted incursion oftheir service range by the drug store carrier.There is no channel available for any newio,ooo-watt stations anywhere.Another hearing is demanded by WJBL of

Decatur, Illinois, operated by a dry goods store,calling for a power increase which would damagethe service of ten stations, including such widelyrecognized stations as WBAL and WJAX.WORD, the Peoples Pulpit Association in

Chicago, seeks to occupy the channel of WTASand WBBM, both well established and servinglarge groups. There is little question but that the

defending stations will be able to show the Com-mission the presumptuousness of those demand-ing these hearings, but it is unfortunate that

lawyers, witnesses and disorganization of stationstaffs are required to do so.

"RADIO INDUSTRY" STANDARDS

LJ B.RICHMOND, Director of the Engineering. Division of the R. M. A., perhaps inspired

by our suggestions as to the desirability of oneset of radio standards rather than two, in anarticle in the R. M. A. News, suggests that theR. M. A. and the N. E. M. A. should combinetheir work of writing radio standards. Although,as Mr. Richmond points out, the R. M. A. hasten times as many members as the Radio Divis-ion of the N. E. M. A., the long engineering ex-perience of the older organization and the greatimportance of the manufacturers comprising it,makes its cooperation in writing standards ofvital importance. Mr. Richmond's fair expositionof the situation is a long step toward affecting aconsolidation of the standards committees ofboth organizations, vitally necessary if either ofthem are to be in the least effective.

WHY THE SOUTH HAS FEW STATIONS

OENATOR Simmons of North Carolina re-J

cently launched an attack upon the FederalRadio Commission, declaring that it showedfavoritism to stations in the North. Illinois,Nebraska and Missouri, with a population offourteen million, have more licenses to broadcastthan the eleven states of the south with their

population of twenty-seven million.The Senator is correct in his facts, but he dis-

regards the point that the south has not been

sufficiently progressive to erect its share of sta-tions with the consequence that the Northernershave already filled their wavelength bands. Solong as the Commission disregards future needsby filling the ether bands with New York and

108 RADIO BROADCAST DECEMBER, 1927

Chicago stations, there is not room enough forbetter broadcasting service in the more remote

areas.

HOW THE RADIO BEACON WORKS

1'HEradio beacon operated at Hadley Field,

New Jersey, the terminus of the New York-San Francisco air mail route, has proved re-

markably satisfactory. Two directional antennasare used, set at right angles. By means of amechanical keying device, the letter "A" (dotdash) is sent from one antenna and the letter"N" (dash dot) is sent from the second. Thetransmissions are so timed that the dots anddashes exactly interlock so that, at the pointswhere the signals from both transmitters arereceived equally, a continuous dash is heard.That point of equal signal strength is exactlymidway between the directional signals of thetwo antennas. The radio listener aboard the

plane can determine from the signals he hearswhether he is exactly on the course or to the rightor to the left of his course, because, in the former

case, he will hear the steady dashes, while off his

course, he will hear either A or N, depending onwhether he is to the left or the right of it. Thecloser to the landing field he approaches, the

more narrow the midpoint at which the signalsare heard to form dashes. A few hundred feetfrom the beacon station, a deviation of ten or

twenty feet from the course is clearly indicated

by the signal in the headphones.

THE NEW WEAF TRANSMITTER

INSPITE of its 50 kw., the initial broadcasts

of WEAF at Bellmore proved a disappointmentto many New York listeners who have dependedupon WEAF for their principal program service.There are large areas within twenty-five milesof New York which, due to the change of loca-tion, now receive a weaker signal from the jo-kw.transmitter than they did from the old 5-kw. at

West Street. There have been other instanceswhen the removal of stations, even a short dis-tance from the congested areas to permit increaseof power, have actually reduced the number of

persons served.

The transmitting apparatus at Bellmore is thelast word in perfected control. The operator in

charge sits before his desk and manipulates anumber of buttons controlling each operation inthe station, which has the proportions of a fairsized power house. If one of the water-cooled

rectifier, oscillator or modulator tubes burns out,a light indicates the faulty tube. Pressure of a

control button takes it out of service and connectsa substitute without interruption of broadcast-

ing.The receiving set used to maintain the sos

watch has a range of several thousand miles andwill be used to advantage by WEAF'S operator.WEAF'S sos watches already have the remarkablerecord of being the first to hear sos calls in the

New York area and notify naval and coastguards in one case out of each three and of hear-in the sos simultaneously with naval and coast

guard stations in the same proportion. Most

broadcasting stations continue blithely on theair through sos calls until the silence of the etheraround them impresses them with the fact thatthere must be something wrong.

NEWS OF THE PATENT FIELD

CLEVEN claims of F. A. Kolster's patent*-< 1,637,615, were declared invalid in a decision

by the Second Assistant Commissioner of Patentson the grounds that the applicant's combinationclaim to a radio compass having a coil form ofantenna was not novel and was well known at the

time the applicant entered the field, f t f THEPATENT Office Gazette mentions the followingsuits over radio patents: Westinghouse vs.Allen Rogers, Armstrong 1,113,149; Radio Fre-

quency Laboratory, Inc. vs. Federal Radio Cor-

poration, Warren patent 1,603,432. ? f I THEDUBILIER Condenser Company has filed againstthe Radio Corporation of America on varioussocket power patents, f f ? JOHN V. L. HOOANfiled against the American Bosch Magneto Com-pany, Stewart Warner Corporation, Freed-Eisemann, Freshman, and Splitdorf for recogni-tion of his patent 1,014,002, and also against a

large department store for its sale of Crosley,Stromberg Carlson, Federal and Fada sets whichhe alleges infringe his basic patent. I f I A. H.

GREBE and Company, Stewart-Warner, and theConsolidated Radio Corporation (Wells Gard-ner, Chicago and Precision Products Company,Ann Arbor, Michigan) are now R. C. A. licensees.

The Month In Radio

THEEastman Kodak Company suggests

that RADIO BROADCAST encourage the useof the term "phototelegraphy" rather than

"telephotography" in referring to the radiotransmission of pictures. "Telephotography" isused among photography experts to denote the

taking of pictures over long distances by the useof special lenses, although Webster approves theuse of the term to describe the transmission of

pictures by radio or wire. Indeed, so extensivehas been this latter use in scientific circles thatit would require much more than the approval ofRADIO BROADCAST to bring about a change inthe accepted terminology. Perhaps a compromisemay be suggested which may help to eliminatethe confusion. Why not refer to telephotographyin the sense of transmitting pictures by wire orradio, as "radio photography" or "wire phot-ography," as the case may be? Iff RADIO willperform a new feat in eliminating the isolation of

explorers when the Army Signal Corps and thePathe Company participate in their explorationof the Grand Canyon of the Colorado. The expe-dition will traverse the entire length of the canyon,

taking moving pictures and collecting data ofscientific and educational value. Accompanyingthe explorers will be a radio telephone trans-mitter which will be used tolink them with broadcastingstation KGO, from which

reports will be broadcast

through a chain of stations.The explorers will venture intodangerous and heretofore in-accessible parts of the canyon.Iff WE NOTE in the listof changes ordered by theFederal Radio Commission,authorization to move KFKXfrom Hastings, Nebraska, to

Chicago, Illinois. KYW hasshared its channel with KFKX.The result of the move is togive Chicago listeners the fulluse of the channel without

increasing station congestion.Nebraska and the great openspaces, however, suffer acurtailment of broadcastingservice, f f f KOIL is now

transmitting its regular pro-grams on 491 o-kc. (61.06 met-

ers), as well as its regularchan-nel in the broadcasting band.

KOIL is a member of the Columbia chain, f * tTHE MACKAY Companies purchased the FederalTelegraph Company's communication system,according to a recent announcement. The Fed-eral Company's equipment consists of high pow-ered arc stations installed along the Pacific

Coast for point-to-point service in California,

Washington and Oregon, and ship-to-shore ser-vice on the Pacific, f f f WE ARE opposed tothe radiation of the same program by stations

covering the same service area. The listener is en-titled to as much variety as the congested etherpermits and the employment of two channels todo what may be done effectively with one is awaste of ether space. This practice is frequentlyindulged in by chain stations. ? f f ANOVELUSCof broadcasting was employed by the UnitedGas Improvement Company of Philadelphia towarn its customers that gas service had been

temporarily discontinued because of damage byan accidental blast. Undoubtedly, this preventedmany accidents upon the resumption of service.f f I THE American Agriculturist should beable to write a volume on the service of radio tothe farmer as a result of the contest which it

recently announced. It offers not too large prizesto farmers writing the best letters on the servicewhich radio renders them. There have been manyinstances of thousands of dollars of savingthrough weather and market information, f t If f I BROADCAST LISTENERS in Germany nownumber 1,713,899, according to Wireless Age, anincrease of 78,171 in a three months' period.t f f THIRTY MILLION dollars worth of radio

apparatus was involved in international trade in

1926, of which about thirty per cent, consisted ofAmerican shipments, twenty-five of German,and twenty per cent, of British. Exports from theUnited States decreased twelve per cent, in 1926as compared with 1925, but the figures for thefirst half of this year show a revival of business.

During the first half of 1927, American exports,were $3,705,861, an increase of $450,000 overthe same period for the previous year. IffOUR BRITISH contemporary, Popular Wireless,made some measurements as to the radiationrange of a two-tube receiver, consisting of one

stage of r. f. and detector. The set was presum-ably a non-radiating one, but actually its radia-tions were readily heard at a distance of twelve

miles, although but fifty volts of plate batterywere used. The radiations were found to blanketan area of nearly two hundred square miles inwhich some five million people reside.

A TUG CAPTAIN WHO CAN TELEPHONE FROMHIS BOAT

More than forty British-Columbian tug-boats, used in towinglumber on the waterways, are equipped with 5O-watt radiophonesets, tuned to 1507 kc. (199 meters). The view above shows aCaptain's cabin and the complete receiving and transmitting

installation

1T1-JT1C1 17/01 TIC?UrUi JriJUil

AN ENGLISH SHIELDED-GRID TUBEIn England and on the Continent, four-electrode tubes have been available forsome time. The original research is credited to Schottky in Germany and the"shielded-grid" tube which has recently appeared in this country is credited toDr. A. W. Hull

By THEODORE H. NAKKEN

AREVIEW of the progress of receiverdesign, which is possible by turningover the advertising pages of some earlyradio magazines, would offer some surprisingevidence. We would see that mechanical im-provements, refinements, and modern methodshave been the cause of radical changes in receiverpattern, and have so simplified operation oftuning as to make the modern receiver seemas far in advance of its forbears as is the present-day automobile ahead of the automobile offifteen years ago. Yet we would note that therehas been no basic change in the type of circuitused. The regenerative receiver of ten years agostill stands unchallenged as a sensitive device for

translating signals from a distant broadcastingstation.

In searching for the reason of this lack ofchange in circuit arrangement, it will occur tous that we have reached a limit, and that it isalmost impossible to obtain greater amplifi-cation than the present-day receiver gives us.And this limit is easily located as lying in theinherent characteristics of the vacuum tube asmanufactured to-day. Even with its better fila-ments and better all round design, the vacuumtube of to-day has exactly the same funda-mental characteristics as it had when first con-ceived and built as an experiment. It follows,then, that if any improvements in receivers areto be expected, such improvements will not berealized before radically improved vacuum tubesare made available.

But if we boldly lay the lack of actual progressat the door of the commercial vacuum tube, wemust state why the tube should be responsibleand how its inherent faults can be eliminated.The indictment against the present-day vacuumtube covers in the main two points lack ofamplification and the tendency to cause oscil-lations due to inter-element capacity. Anothercharge that may be brought forward is in-efficiency, but this is almost identical with itslack of amplification. How to improve theseconditions seems at the present time moreimportant than all other efforts combined tomake better receiver circuits, and so we will tryto indicate shortly why the vacuum tube isinefficient, and how we can largely do away withthe inter-element capacity, so as to get betterall around performance from any circuit.The ordinary vacuum tube contains three

elements filament, grid, and plate. The fila-ment acts as a source of electrons when heated;the plate, by virtue of its positive potential,causes these electrons to be attracted to itselfand thus establishes a plate current; the grid,

interposed between filament and plate, governsthe amount of electrons that can reach the plate,acting, therefore, as a controlling element of theplate current. The grid, generally being held at anegative potential, tends to prevent electronsfrom wandering away from the source (thefilament). The plate attracts electrons only byvirtue of its high positive potential, and over-comes the repelling effect of the grid.

Space ChargePlate Field +

"-GridField-

FIG. I

In the three element tube there are three staticfields which govern the tube's functions. Fromthis diagram it is seen that there are two negativefields, both of which impede the flow of electrons

to the plate

It is not only the grid that tends to repel theelectrons emitted by the filament but this repel-lent action is also exercised by the electronsthemselves. In fact, we may say that the fila-

FOR the last four years, foreign radio periodi-cals have contained a wealth of articles onthe advantages of the double-grid lube. These tubesare chiefly used by ourforeign neighbors because oftheir economy, but it has been inevitable that theselubes should make their appearance in this coun-try. More than a year ago, two manufacturersbrought sample double-grid tubes to the Laboratorybut the time was not yet ripe for their general in-troduction. In April, 1926, Dr. A. W. Hull ofthe General Electric Laboratories described his"shielded-grid" tube in the Physical Review andon October ist the New York newspapers carriedthe announcement of the Radio Corporation that a"shielded" grid tube the ux-222 was 'in theprocess of commercial development and would beready for the general public "some time in thefuture." Believing that our readers would be inter-ested in a review of important information ondouble-grid tubes, thefollowing article was preparedat our request by Mr. Nakken who is familiar withthe use and operation of multi-grid tubes on theContinent. THE EDITOR.

ment is surrounded by a cloud of electrons, whichtherefore constitute a negative charge, trying todrive the electrons back instead of allowing themfree passage to the plate. See Fig. i. Hence theplate must not only overcome the effect of thenegative grid, but it also must nullify the effectof this cloud of electrons, which generally iscalled the space charge, in addition to its dutyto attract electrons and thus establish the platecurrent.

There are two combined factors then whichtend to retard the flow of electrons from filamentto plate space charge and the grid, and bothare counteracted by the plate potential. Itfollows that part of the plate potential is utilized

only to overcome the repellent action of spacecharge and grid, and of course, as far as amplifi-cation goes, this part of the plate potential is

virtually useless. We may then say that thestatement to the effect that the tube is inefficientis proved, the more so when it has been estab-lished that, in most designs, only from 10 to 15per cent, of the plate potential is actually avail-able for the establishing of plate current, andthe remaining potential serves the purposeindicated.We know that the space charge is virtually a

constant and its effect is added to that of thegrid effect. The space charge, having its sphereof influence much nearer to the source of elec-trons than the grid, is much more powerful in itsaction, and thus a variation in grid potential,while representing a comparatively large changeof the grid action on the flow of electrons, isdecreased in its effect by the fact that it repre-sents only a comparatively small change in thetotal sum of the retarding action of grid andspace charge combined. Here again we may saythat the tube is proved to be highly inefficient,but now in the sense that the presence of thespace charge prevents the grid from being fullyeffective.

It follows from the foregoing remarks that themain reason for the inefficiency of the vacuumtube may be sought in the presence of the spacecharge. In fact, if the latter were absent, wewould need only a small plate potential to obtainthe identical results as at present, with theadditional advantage that the grid would befully effective because the grid field would be theonly factor governing the magnitude of the elec-tron flow to the plate, instead of only part of thesum of two factors, of which the second one, thespace charge, is by far the greater. The truth ofthe matter is that, if only the space charge wereabsent, the grid effect would be from three to fourtimes greater than at present, i.e., without any

110

further changes in the tube the amplificationfactor would jump from, say, 8 to 30, yet theinternal impedance of the tube would remainthe same

THE FOURTH ELEMENT

WHEN we consider the static fields presentin the vacuum tube we will see that wecan count three space charge, grid field, andplate field. The former two are negative whilethe latter is positive. The space charge, as wehave seen, is a constant, or virtually so, and mustbe nullified by part of the positive plate field.If, then, a second positive field were introduced,nearer the filament, and thus nearer the spacecharge, a fairly low potential field would easilynullify the latter's effect. Obviously this caneasily be done by a fourth element, whichwould, of necessity, be placed either betweenfilament and grid, or between grid and plate.This element, however, should not obstruct theflow of electrons from filament to plate, hence itshould be an open structure, and for this reasonlogically take the form of a veryopen grid. In this way the four-element (double-grid) tube wasborn.

Let us consider for a mo-ment that such a grid is placedbetween filament and grid,as in Fig. 2. Due to the con-struction of the tube it is muchnearer the filament than the

plate, and as the influence ofsuch a field is inversely propor-tional to the cube of the distance,it becomes apparent that, if thisgrid is placed at, say, one thirdof the distance between filamentand plate, its field is 27 timesmore effective than the platefield. Thus, if in the ordinarytube 90 volts is used on the

plate, approximately 3 volts would suffice onthis fourth element to completely do awaywith the space charge effect. This, first of all,increases the percentage effectiveness of any

RADIO BROADCAST

Auxiliary Fiel'

Space Charge-,- Plate Field +

Grid Field -

Auxiliary Field +

Space Charge -

FIG. 2

When an auxiliary positive field is introducedinto the tube, the negative field due to the fila-ment is overcome, leaving the total negativefield (which is detrimental to the progress of elec-trons to the plate) in a much reduced condition

potential change on the controlling element, thegrid proper, so that we reach automatically amuch higher amplification factor, and secondly,

Milestones in Vacuum Tube ProgressEdison discovered "Edison Effect" ....Fleming experimented with Edison Effect .Fleming patented the two-element rectifier tubeDeForest added third element to Fleming valveTubes used in transcontinental telephony .Radio telephony from Arlington to Honolulu .Introduction of "hard" tubes to general use .Appearance of thoriated filaments 1923 ,General use of power tubes 1926 IDevelopment of high-current low-voltage filaments 1927 IDevelopment of shielded-grid tube 1927 \

FIG. 3This diagram is that of a single radio-frequencyamplifier using a double-grid tube, the inner,grid being at a positive potential with respect tothe filament. The grid-plate capacity remains

unchanged

makes it possible to decrease the plate voltageconsiderably, say to ten or fifteen volts, and stillretain a tube of the same general characteristicsas the three-element original.

It should be noted here, that we have assumedthat this fourth element is built into an ordinarytube. The result then is that we have not in-creased the capacity between the plate and grid,and thus have not increased the tendency of thetube to oscillate due to capacitive feedback.This is a very important consideration, becauseit is easy enough to build an ordinary three-element tube with as high an amplificationfactor, as is done with modern high-mu tubes.But the latter is accomplished by narrowing thegrid, i.e., by increasing the plate-to-grid capacity,and hence such tubes are almost completely un-fit for radio-frequency amplification. In such atube the tendency for capacitive feedback isincreased tremendously, and this capacity affordsan easy path for the signal potentials to escapevia the plate and become ineffective. As will be

DECEMBER, 1927

seen in Fig. 3, there is nothing strange in thehookup of a four-element tube, the extra elec-trode being hooked directly to some part of theB battery.We will now consider the second possibility in

construction, i.e., that of placing the fourth ele-ment between grid and plate. Of course it musttake the form of an open grid, as its purposeagain is only to create a positive field, to be usedto nullify the space charge effect.

Let us suppose that the tube is now so con-structed that this element is placed halfwaybetween filament and plate, in which case itfollows that its effect on the space charge is

eight times greater than the same potential onthe plate. If, then, normally the plate has apotential of 90 volts, a positive potential of 12volts will be equally effective when applied tothe fourth element, so that once more the platevoltage can be decreased to, say, 22^ volts. Dueto its open construction the positive grid offersno obstruction to the flow of electrons, and itselfdraws only a very small current. Once more we

make the grid fully effective inits influence upon the flow ofelectrons, so that the amplifica-tion factor of the tube has been

materially increased.But simultaneously we have

attained another effect, whichmerits close investigation. Thepositive grid, being held at aconstant positive potential bythe expedient of connecting it toa point on the B battery, maybe stated to be constantly at acertain potential above groundpotential. But after all, it is

grounded. As it is interposed be-tween plate and grid, it has theeffect of splitting the capacitybetween these two elements intotwo capacities, in series as can

be readily seen in Fig. 4, because it acts thesame as if a grounded plate were inserted be-tween two condenser plates. And as its structureis very open, its capacity to each of the elements

Hih

1883189619051907191419151920

THE "INNER WORKS' OF AN ENGLISH SHIELDED GRID TUBEOne really ought to call them "shielded-plate" tubes, for the grid differs but little from that inordinary tubes, while the plate is housed behind the shield. This illustration and that which heads

this article are reproduced from Wireless World (London)

FIG. 4If the outer grid of a double-grid tube is madepositive, the resultant grid-plate capacity of thetube is greatly reduced. At the same time it ispossible to build tubes with much greater ampli-fication factor. The plate-grid capacity is reducedowing to the fact that two "condensers" are

now in series

of the tube is very small indeed, smaller in factthan the capacity between plate and grid origin-ally was. As the two capacities are in series, theresultant capacity between plate and grid issmaller than either one of the two, and hencewe have, in this particular construction of the

double-grid tube, almost completely eliminatedthe plate-grid capacity, with all its banefuleffects on receiver efficiency.

Thus, this type of vacuum tube has even

greater advantages than when the positive gridis placed between filament and grid. We havecreated a tube which is highly efficient as to

DECEMBER, 1927 APPLICATIONS OF THE FOUR-ELECTRODE TUBE 111

FIG. 5In this detector circuit the outer grid is positive,the inner grid biased negative to prevent over-

loading

plate potential, its amplification factor has

been increased considerably, and the plate-gridcapacity has been largely eliminated, so thatthe tube may be called self stabilizing.No wonder then that the European amateur

uses these double-grid tubes quite extensively,for the upkeep of a small receiver with tubes ofthis kind is very economical.

Let us for a moment imagine what can be done

PLATE VOLTAGE

FIG. 9Measurements made in the Laboratory of RADIOBROADCAST show that when the inner grid ispositive, the mutual conductance of the tubemay rise to as high as 800 while the plate im-pedance is 125,000 ohms, indicating a voltageamplification factor of 100. Plate voltage-plate

current curves are shown here

1 with tubes of this kind. In an ordinary receiveremploying two r.f. stages we may be glad if we

! get a voltage amplification of about eight per'

radio stage, so that the total amplification beforedetection is only sixty four. With tubes of thisnew design, and an amplification factor of, say,25, we get an amplification before detection of

625 under the same circumstances, and withless trouble, because the capacitive feedback isas much more easily controlled.An ordinary detector gives an additional

amplification of about four, so that with thecommercial receiver and ordinary tube the de-tector delivers a signal with a voltage amplifi-cation of about 250. The new tube as a detectorwould give an amplification of about 12, so thatits signal would represent an amplification of

I 7500 times after the two r.f. stages and this is

I

voltage amplification only.Due to this enormous amplification, the con-

ventional condenser and grid leak should ofcourse be discarded for a negative potential onthe detector grid, as shown in Fig. 5, becauseotherwise the detector would surely be over-loaded.

For audio amplification the type of double-grid tube used is almost immaterial, but as onlythe one type (with extra element between plateand grid) gives great advantage of decreasedinter-element capacity, and thus will be employedin the r.f. stages, we may just as well use it forthe audio stages too. With a good three to onetransformer one stage will give us an amplifi-cation of about 90, so that the total reaches,after the first stage, 675,000, as against

FIG. 6A transformer-coupled audio amplifier stageusing a tube whose outer grid is positive to reducethe space charge and make the plate voltage

more effective

ordinary tubes, with the same transformer, 24for one audio stage and a total amplification of6000. One perceives that almost unlimited per-spectives in receiver design are opened up, that

MH

3

RADIO BROADCASTLABORATORY

UX-222Inner Grid- 22.5

p- MS i

/

1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.2 0.4 0.6 0.8 1.0 1.2.

GRID VOLTS

FIG. IO

Grid voltage-plate current curves on the newux-222 tube with the inner grid positive. Notethat the grid voltage lines are only two tenthsvolts apart indicating a large amplification factor

enormous volume may be expected, and distanceundreamed of may be covered.A study of the diagrams will reveal that the

tubes are hooked up almost in the same way asordinary tubes, with the exception of the posi-

PLATE VOLTAGE

FIG. I I

The most interesting curve of all the platevoltage-plate current data with positive outergrid. Note the negative resistance at low platevoltages, the rapid rise when the plate voltageequals that of the outer grid, and the very flatstraight portion where the tube is ordinarily

worked

FIG. 7A resistance-coupled low frequency ampli-fier with the outer grid of the tube positive

live grid connection. Figs. 6 and 7 show dif-ferent audio stage hookups.The names

"double-grid" tube is in theauthor's opinion, a misnomer. Generally we callthe controlling element the grid, and as thefourth element in no way serves as a controllingelement, it should not be called a grid, but

simply the auxiliary element, or fourth element.Others have called the peculiar action of thefourth element between grid and plate a shield-

no V.

FIG. 8The circuit of a special a. c.-operated doublegrid tube in process of development.

ing one, and call a tube thus constructed ashielded grid tube. It will be perceived that thereis a good reason for this name, because the gridis actually more or less shielded against the plateeffect, causing it to be remarkably stable.

EDITOR'S NOTE

THEcurves presented here were made in the

Laboratory and show the interesting charac-teristics of the ux-222 the R. C. A. "shielded

grid" tube. Followers of our tube articles shouldnote the extremely flat plate-current plate-voltage curve indicating an impedance withthe outer grid positive of about 650,000 ohms,the negative resistance or falling characteristicat low plate voltages, and the high amplificationfactor of 222 secured by multiplying the mutualconductance by the plate impedance. If it ispossible to place a load in the plate circuit ofthis tube, say at broadcast frequencies, of

650,000 ohms, a voltage amplification of 1 1 1 willresult, compared with the usual amplification ofabout 10 for a single tube and its accessoryapparatus.With the inner grid positive, the mutual con-

ductance rises, the plate impedance falls, and theamplification factor drops to about 100. Underthese conditions the tube can be used in a resist-ance or impedance coupled low-frequencyamplifier.

Experimenters will delight in this tube. Its pos-sibilities are many and diverse. It will not revo-lutionize the radio industry, newspapers to the

contrary, nor will it produce an entirely new erain receiver design. 1 1 is just one more step towardthe ultimate goal of what? RADIO BROADCASTwill publish additional data as it is available onthe use of tubes of this type.

The PHONOGRAPH JoinsBy Way of Introduction

\ JOT many months ago, Carl Dreher suggested1 ' in his department in RADIO BROADCAST,that a radio broadcast program was almost themost ephemeral thing in the world. Thousandsof dollars are spent to engage talent, wires

covering half a continent are hired, advertisingis scheduled in newspapers, several studio re-hearsals are held, and finally the elaborate pro-gram is put on the air. For an hour it lasts butit can never be repeated. If you did not hear it,all the king's horses and all the king's mencouldn't put it into your loud speaker again.

If it is not possible to reproduce a completeradio program in one's own home, one can atleast recreate the equivalent. A very great num-ber of well-known radio artists are regularly re-

cording for each of the important phonographcompanies. Their records electrically cut areavailable everywhere.These pages list a few of the records made by

artists who are perhaps better known to theradio listener than to the average purchasers of

phonograph records. Here are fine recordingsmade by the

'

favorities of the Atwater Kent

hour, and the famous artists of the Victor,Brunswick and Columbia hours. As for the jazzbands, the comedy duos, and other enter-tainers with a more local fame, they, too, areforever at your beck and call on the black discs.One of the most important advances made in

recent years for which we must thank thescientists is the great progress made in the re-production of music and speech by electricalmeans. All radio folk know how audio amplifica-tion has been improved, what with new amplifiersof excellent characteristics, better loud speakers,and so forth. An equally important improve-ment has taken place in the phonograph field.Now the phonograph, with its electrically cutrecords and its acoustically excellent exponentialhorns or cone loud speakers, will rival the musical

fidelity of the best radio receiver.

NEW RECORDS BY RADIO FAVORITESReleased Since September

WHAT no WE Do ON A DEW-DEW-DEWY DAYIs IT POSSIBLE?THE TAP TAPIF I HAD A LOVERPRESIDENT COOLIDCE WELCOMES COLONEL LINDBERGH AT

WASHINGTON, D. C., JUNE 11, 1927 PARTS i AND 2PRESIDENT COOLIDGE WELCOMES COLONEL LINDBERGH AT

WASHINGTON, D. C., JUNE n, 1927 PART 3COLONEL LINDBERGH REPLIES TO PRES. COOLIDGECOLONEL CHARLES A. LINDBERGH'S ADDRESS BEFORE THE

PRESS CLUB OF WASHINGTON. D. C , JUNE 1 1, 1927COLONEL LINDBERGH'S SOUVENIR RECORD ConcludedCIRIBIRIBIN (WALTZ SONG)IL BACIO (THE Kiss) (ARIDTI)INDIAN LOVE CALL (FROM ROSE-MARIE)ROSE-MARIE (FROM ROSE-MARIE)OLD BLACK JOE (FOSTER)UNCLE NED (FOSTER)ACTUAL MOMENTS IN THE RECEPTION TO COLONEL CHARLES

A. LINDBERGH AT WASHINGTON D. C., PARTS i AND 2AT DAWNINGTHE WALTZING DOLLKENTUCKY BABEMIGHTY LAK' A ROSEANGELS WATCHING OVER MECLIMBIN* Up THE MOUNTAINSAM'S BIG NIGHTTHE MORNING AFTERJUST LIKE A BUTTERFLYJUST ANOTHER DAY WASTED AWAYUNDER THE MOONSING ME A BABY SONGYou DON'T LIKE IT NOT MUCHOH JA JA

Shilkret-Victor OrchestraKentucky SerenadersKahn's OrchestraShilkret and Victor Orchestra

Hon. Calvin Coolidge

Hon. Calvin Coolidge

Colonel Charles A. Lindbergh

Colonel Charles A. Lindbergh

Bori

Virginia ReaMurphyTibbett

Victor Concert Orchestra

Vaughn De Leath

Utica Jubilee Singers

"Sam 'n' Henry"

Franklyn BaurMarvin-Smalle

Stanley-MarvinVaughn De Leath

The Happiness Boys

20819

20827

35835

35836

35834

1262

4015

1265

20747

20668

20664

20665

20788

20758

20787

20756

Vidm

The public has suffered rapid education. Theyhave learned that faithful reproduction of the

original is possible in radio sets and in phono-graphs alike. And if the growth of broadcastingwere not enough to sharpen the interest inmusic of all kinds, the new phonographs and thenew records have come along to broaden thedomestic entertainment horizon.The radio receiver has taken its place as a

musical instrument a medium of entertain-ment along with the phonograph and the piano.The radio set in the public consciousness is no

A COMBINATIONRADIO-PHONO-GRAPH FROMBRUNSWICK

The BrunswickPanatrope.Radiola,model ijSC. Thisinstrument con-tains a Radiola 28super-heterodynereceiver with en-closed loop, whichcan be controlledby the dial in thefront of the left-hand panel. On theright is the Pana-

trope and below itthe cone loud speak-er working out ofa ux-2io amplifierwhich is also theamplifier for theradio set. The in-strument, completewith all tubes for6o-cycle a. c. oper-ation lists at $i 150

longer merely a scientific marvel and mystery.And since they are so closely related because ofwhat they can bring to the home, the phono-graph and the radio set have been drawn closelytogether in association of ideas and in actualphysical form. Those who wish to buy a combina-tion radio-phonograph can choose many finemodels from five or six well-known manufactur-ers. Those who already have a radio receiverwhich they wouldn't trade for the royal throneof Roumania can make their audio amplifier andloud speaker do double duty in reproducingphonograph records or a radio program accord-ing to the whim of the owner. All one needs be-side a good loud speaker system is any kind ofturntable which will twist the record at an evenspeed of 78 revolutions per minute, and a goodelectro-magnetic pick-up. And there are many ofthe latter on the market.

FAVORITES IN CHICAGO"Sam 'n' Henry" Correll and Gosden whonightly disport before the twin microphones ofWON and amuse countless WON listeners. Theirverbal antics are embalmed on Victor records,

listed above

DECEMBER, 1927 113

the RADIO SetNew Records by Radio Favorites

SOMETHING TO TELLSTOP, Go!I AIN'T GOT NOBODYROODLESMY WIFE'S IN EUROPE TO-DAYA LITTLE GIRL A LITTLE BOY A LITTLE MOONBABY FEET Go FITTER PATTERSOMETIMES I'M HAPPYWHEN DAY Is DONENo WONDER I'M HAPPY

AIN'T THAT A GRAND AND GLORIOUS FEELING?MAGNOLIA

JUSTA MEMORY (VOCAL CHORUS BY ELLIOT SHAW)

OY BELLS (VOCAL CHORUS BY VAUGHN DE LEATH)OOH! MAYBE IT'S You {VOCAL CHORUS BY FRANKLYN BAUR)SHAKING THE BLUES AWAY (VOCAL CHORUS BY FRANKLYN BAUR)JUST A MEMORYMY HEART is CALLINGNo WONDER I'M HAPPYJUST ONCE AGAIN

BABY FEET Go FITTER PATTERTHERE'S ONE LITTLE GIRL WHO LOVES MEFANTASY ON ST. Louis BLUES

PARTS i AND 2AIN'T THAT A GRAND AND GLORIOUS FEELING?I AIN'T THAT KIND OF A BABYLEONORAPARES!HERE AM I BROKEN HEARTEDHAVANA(VOCAL CHORUSES BY FRANKLYN BAUR)SWANEE SHOREMEET ME IN THE MOONLIGHTDo You LOVE ME? VOCAL CHORUS BY F. BAURHONEY VOCAL CHORUS BY VAUGHN DE LEATHAIN'T THAT A GRAND AND GLORIOUS FEELING?Vo-Do-Do-DE-O BLUESTHAT SAXOPHONE WALTZ1 COULD WALTZ ON FOREVER WITH You SWEETHEARTGio-Ap, GARIBALDIOH! YA! YA!FOR THEE (POUR Toi) (GORDON)FROM OUT THE LONG AGO (STRATTON AND DICK)IUST ONCE AGAIN (CHORUS BY F. BAUR)LOVE AND KISSESARE You HAPPY?GIVE ME A NIGHT IN JUNESONG OF HAWAIIHAWAIIAN HULA MEDLEYTwo BLACK CROWS, PART }Two BLACK CROWS, PART 4MAGNOLIAPASTA FAZOOLATHE VARSITY DRAG

(VOCAL CHORUS BY BAUR, JAMES, AND SHAW)DANCING TAMBOURINEGOOD NEWS (VOCAL CHORUS BY BAUR, SHAW AND LUTHER)LUCKY IN LOVE

Shilkret-V'ictor Orchestra

Coon-Sanders Orchestra

Fry's Million Dollar Pier Orch.

Vaughn de Leath

Radio Franks,White and Bessinger

Harry Richman

Harold Leonard and His Waldorf-Astoria Orchestra

Harry Reser's Syncopators.

Franklyn Baur

Ernie Golden and His HotelMcAlpin Orchestra

Abe Lyman'sCalifornia OrchestraDon Vorhees and His Earl Car-

roll's Vanieties Orchestra

Paul Ash and His Orchestra

Leo Reisman and His Orchestra

Cass Hagan and His ParkCentral Hotel Orchestra

Harry Reser's Syncopators

The Columbians

Van and Schenck

Art Gillham-The WhisperingPianist

Billy Jones and Ernest Hare(Happiness Boys)

Barbara Maurel

Paul Ash and His Orch.

Ipana Troubadours

South Sea Islanders

Moran and Mack

Van and Schenck

Cass Hagan and His ParkCentral Orchestra

The RadiolitesFred Rich and His Hotel Astor

Orchestra

3590 Brunswick

3605

10780 Columbia

io66D

10830

10890

10870

io68D

10710

1081 D

10740

1 4oM "

10900"

10980

n n D

10940 "

10920 '

11140 Columbia

lloSD

THIS RADIO PROGRAM IS RECORDEDColonel Lindbergh before the Washingtonmicrophones which carried his welcome-homeceremonies to the entire nation. Victor has madefour excellent records from this event.

FORthe first time, phonograph records of a

radio broadcast program are offered to the

public. Victor has the distinction of pioneeringand they offer three double-face records of thenational welcome to Colonel Charles A. Lind-bergh at Washington. On these three records youhave the voice of President Coolidge, the inter-spersed announcements of Graham McNamee,a short address by Colonel Lindbergh, and hislonger speech at the National Press Club. It'sall there and if you close your eyes, it isn't hardto imagine that the events are just taking placethe cheers of the crowd, the applause whichinterrupts the speakers, the blare of the bands,and the quiet unruffled voice of Lindbergh.The Victor Company arranged a direct wire

from Washington, culminating in their studiosthrough which their recording apparatus got thesame program as each of the broadcasting sta-tions. The ceremonies were recorded on forty-sixrecord surfaces and finally edited down to thesix surfaces now available. It is a good job fromany point of view and Victor is to be congratu-lated. It is time that some of the historic eventswhich are being offered to the radio listener withimpressive regularity were preserved in perman-ent form. The next offering will be a champion-ship fight, we suppose.

GUESS WHONone other than Billy Jones and Ernest Hareknown to Eastern listeners of WEAF on Fridaynights as the Happiness Boys. Their songs arerecorded by Victor and Columbia

A PHONOGRAPH-RADIOCOMBINATION FROM

VICTOR"Automatic Electrola-Rad-iola No. 955" is what Vic-tor calls this beautifulinstrument. Records arechanged automatically andgroups of 12 can be playedwithout attention.An 8-tube super-heterodynewith enclosed loop operatingentirely from the light sock-et through the power supplyfor the vacuum tube ampli-fier and the cone speakerused alike for phonographand radio reproduction. Theradio receiver panel can beused in three positions. List

price, $1550

THISarticle is the third in the serifs explain-

ing the use and operation of the Cooley"

Ray-foto" picture receiving system. The Cooley ap-paratus was demonstrated in actual operation atthe New York Radio show and attracted an as-tounding amount of interest. Governor Alfred E.Smith of New York, who made the opening addressof the Show, transmitted a part of a picture ofhimself, reproduced by the Cooley system over wizand other stations of the Blue network. Many ofthe readers of this article undoubtedly heard that

interesting broadcast. The subject of radio photo-graph reception is so large that it can be discussed

only in part on each article. Our readers are ad-vised to preserve carefully each of the articles in

RADIO BROADCAST on this system, beginning i^itbthe first story in the October, 1927, issue. Pictureswill be sent by broadcasting stations, using their

regular assigned wavelength, and no tuning changesin your present receiver are necessary. Readers are

urged to write us their experiences with the con-struction of the recorder. The development of the

Cooley "Rayfoto" system opens for the first timeto the American experimenter an important "nextstep" in radio development.

THE EDITOR.

THEarticles on the Cooley "Rayfoto"

system in theOctober and November issuesof RADIO BROADCAST explained how the

system works, told something of the results tobe expected, and gave some details regardingthe operation of a picture receiver. This thirdarticle in the series gives some general and

particular information about the system, and

diagrams necessary for the construction of a

Cooley receiver are also presented.Many of the units for use in the radio picture

receiver have been especially designed for the

purpose and therefore possess the necessarycharacteristics for good results. They have beendesigned to take care of the present requirementsof the receiver and are so flexible that they willstill be suitable for use as the system may begradually developed. Considerable care hasbeen taken in this matter so that it will not be

necessary to scrap any of the parts as the natural

development of increased speed of reproductionand better quality are consummated. Theapproved parts, which have all been carefullytested, are made under the Cooley

"

Rayfoto"trade mark.

Arrangements are now under way to supplyvarious broadcasting stations with phonographrecords which will enable them to put Cooleypictures on the air. The radio editor of your localnewspaper is the best source of information.The complete set-up for picture reception by

means of the Cooley system consists of threedistinct units the radio receiver proper, the

amplifier-oscillator unit, and the printer as-sembly. The first the radio receiver should becapable of quality reproduction of radio pro-grams for if it falls down in this respect it willassuredly do so when called upon to detect andamplify the incoming modulated wave whichhas super-imposed upon it the audible note

representing the picture being transmitted.

Passing from the last audio stage of the re-ceiver proper, the "picture signal" is further

amplified in the amplifier-oscillator unit andit then modulates the output of the oscillator inaccordance with the modulation produced bythe picture. The varying output of the oscillatoris made to cause corresponding variations in theoutput of the corona coil, and thus the intensityof the needle point discharge is made to producean effect on the proper tallying with the original

By AUSTIN Q. COOLEY

picture. The corona coil is included in the secondunit although the actual needle at which the

discharge occurs is naturally a part of the thirdthe printer-unit. This third unit consists of theneedle, the drum upon which the photographicprinting paper is wrapped, and the mechanismwhich causes the drum to revolve. It is purchas-able as a whole, for there are few who possessthe mechanical ability and facilities for theconstruction of such an intricate piece of mechan-ism.The construction of the amplifier-oscillator

unit from the approved parts is a simple matter.

Fig. I shows a suggested layout while Fig. 2is the schematic diagram. The following parts arenecessary for this unit:

TI"

Rayfoto" Amplifying TransformerRi Variable Shunt Resistance for Primary of TIR2 2OO-Ohm Variable Resistance Capable ofCarrying too Mils.

Ra i2-Ohm Filament Rheostat, i-AmpereCapacity

Rr "Rayfoto" RelayTj "Rayfoto" Modulation TransformerCa o. i-Mfd. CondenserRi o.oi-Meg. Grid Leak and MountingCi, Q o.ooo5-Mfd. Fixed CondensersC4 o.ooo5-Mfd. Variable Condensers.

LI "Rayfoto" Corona CoilL2 Radio-Frequency Choke CoilSi Filament Switch$2 Push Button or Special Switch

Ji, J2, Js Double Contact Short-CircuitingJacks

R6 Filament Ballast ResistanceOne Telephone PlugMilliameter, o-aj-mil. ScaleTwo SocketsFourteen Binding PostsBase- BoardPanelBrackets

"Rayfoto" Printer Unit

Although wide deviations from the layoutshown in Fig. i are permissible, it is also quitepossible that considerable "grief" will be experi-enced in many cases where original schemes areattempted. We therefore suggest that the homeconstructor follow our plan of layout and con-struction very religiously, at least on his first set.

The photographs indicate very clearly thearrangement of the apparatus and the experi-enced home constructor should have littledifficulty in putting the apparatus together.

All but the radio-frequency circuits may bewired up in any convenient manner. We find

PICTURES RECEIVED BY THE COOLEY SYSTEMThese two photographs have not been retouched and were received at the demonstration at theNew York Radio Show. Governor Smith, in his radio address opening the Show let radio listenershear how his picture, above, sounded. The heading above shows Mr. Copley and a part of his appara-

tus as set up in operation at the Show. Governor Smith's picture is on the receiving drum

MAKE YOUR OWN RADIO PICTURE RECEIVER 115that ordinary No. 18 rubber covered fixture wireis very easy to handle and makes a reasonablyneat job. Each circuit should be properly testedout, as will be explained later, before the wiresare laced up in bundles. The radio-frequencycircuit should be wired up with considerablecare, the use of bus bar wiring or rigid wires

having a fair amount of spacing between them,being recommended. No particular care need betaken to prevent losses in the radio-frequencyoscillator circuit. The secondary of the coronacoil, and its lead to the corona needle, however,

require very special attention. This subject willbe covered in another paragraph.When the "Rayfoto" printer has been com-

pleted and set up with all connections to batter-ies, proceed as follows for testing and adjusting:

Place two 2O1-A type tubes in the sockets andsee that the filaments are properly lighted and a

good range of brilliancy is controlled by therheostat, Rs, of the amplifier tube. With theinput terminals open, plug a pair of phones inmeter jack, J 2 , for th